water can be decomposed by electrolysis - Edexcel - GCSE Chemistry - Question 4 - 2011 - Paper 1
Question 4
water can be decomposed by electrolysis.
Hydrogen and oxygen are formed.
This apparatus can be used to carry out the electrolysis.
(i) Write the balanced equation f... show full transcript
Worked Solution & Example Answer:water can be decomposed by electrolysis - Edexcel - GCSE Chemistry - Question 4 - 2011 - Paper 1
Step 1
Write the balanced equation for water decomposing to form hydrogen and oxygen.
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Answer
The balanced equation for the electrolysis of water is:
2H2O→2H2+O2
This reaction shows that two molecules of water decompose into two molecules of hydrogen gas and one molecule of oxygen gas.
Step 2
Describe the test to show that a gas is hydrogen.
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Answer
To test for hydrogen gas, you can use a burning splint. When the splint is introduced to the gas, it will produce a distinctive 'pop' sound if hydrogen is present. This indicates that hydrogen is flammable and reacts with oxygen.
Step 3
Describe the test to show that a gas is oxygen.
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To test for oxygen gas, a glowing splint can be used. When the glowing splint is placed in the presence of oxygen, it will reignite or relight, indicating the presence of oxygen. This is due to oxygen's role in supporting combustion.
Step 4
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
The toxic gas produced is:
B) chlorine
Step 5
Give a safety precaution that should be taken when collecting this toxic gas.
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A safety precaution when collecting toxic gases, such as chlorine, is to work in a well-ventilated area or under a fume hood. This minimizes exposure to harmful fumes.
Step 6
Give the name of the acid that must be used.
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Answer
The acid that must be used is hydrochloric acid (HCl).
